1. Field of the Invention
The present invention relates to a webbing retaining structure employed in a seatbelt system for a vehicle designed to restrain the body of an occupant in an emergency situation of the vehicle, for the purpose of retaining a webbing secured to a seat of the vehicle.
2. Description of the Related Art
In occupant restraining seatbelt systems for vehicles, it is preferable that an occupant restraining webbing should be in close contact with the body of an occupant at all times and be able to move to an optimum position in accordance with the driving position or posture of the occupant. To meet these requirements, it is desired to secure one end of the webbing to a seat so that, when the occupant adjusts the position of the seat relative to the body of the vehicle in, for example, the longitudinal direction of the vehicle, the webbing is movable in response to the movement of the seat.
However, when the webbing is secured to the seat, the following problems arise. Namely, the seat is subjected to a relatively large tension which is generated in the webbing by the inertia acting on the occupant's body when an emergency situation of the vehicle occurs. Therefore, it is necessary to increase the strength of the seat by a large margin, and this leads to an increase in the weight. In addition, when a shoulder webbing is mounted on a seat, the end of the webbing is secured to the seat back of the seat and since the seat back is supported in a cantilever fashion, that is, the seat back is supported by the seat cushion at one end thereof alone, it is difficult to increase the strength of the seat by a large margin.
To overcome the above-described problems, a reinforcing structure has already been proposed in which the upper end portion of the seat back is secured to the side wall of the vehicle body through a reinforcing member. This prior art structure, however, undesirably allows the seat back to have a large degree of freedom of movement, so that the reinforcement is incomplete.